[Behavior of the middle ear mucosa in cholesteatoma and following tympanoplasty. An experimental histological study in rabbits].

After operation three consecutive phases can be observed: 1. thickening of epithelial cell layer with development of edema in the submucosa, 2. metaplasia of epithelium with formation of ciliated and goblet cells, concomitantly round cells are found in the submucous tissue, 3. regression of inflammation and epithelial metaplasia. After 6 months goblet and ciliated cells disappear and eventually a slightly irregular monolayer epithelium is seen. If cholesteatoma is present the second phase persists. Remarkably epithelial and subepithelial changes are not concentrated in the vicinity of cholesteatoma but are seen in the whole middle ear. By autoradiography it was demonstrated, that the subepithelial tissue of cholesteatoma has a normal metabolic rate. It can be concluded that high metabolic activity postulated by other authors cannot be responsible for inflammation.